The present application relates to embedded high performance magnetoresistive random access memory (MRAM) devices, and more particularly to a multilayered hardmask for a MRAM device that prevents degradation of the performance of a magnetic tunnel junction (MTJ) structure of the MRAM device.
MRAM is a non-volatile random access memory technology in which data is stored by magnetic storage elements. These elements are typically formed from two ferromagnetic plates, each of which can hold a magnetization, separated by a thin dielectric layer. One of the two plates is a permanent magnetic set to a particular polarity; the other plate's magnetization can be changed to match that of an external field to store memory. Such a configuration is known as magnetic tunnel junction (MTJ).
In leading-edge or neuromorphic computing systems, a MTJ structure (or pillar) is typically embedded within a back-end-of-the-line (BEOL) structure and a metal hard mask is typically formed above a multilayered MTJ structure, and the metal hardmask is used as an etch mask to provide the MTJ structure. Halogen-based metal hardmask etching is typically used to provide an optimal MTJ structure profile. However, halogen diffusion into the metal hardmask degrades the magnetics of the MTJ structure. One current solution to this problem is to employ a thicker metal hardmask. However, such a solution does not mitigate the problem as future nodes need the MTJ structure height to scale. Thus, there is a need for providing a hardmask structure that can circumvent halogen ion diffusion into the MTJ structure, without negatively impacting scaling.